The study involves patients with the Prader-Willi Syndrome and patients with simple exogenous obesity as controls. During the past year two studies were initiated: 1) Study of plasma and RBC bound endorphin in both groups of patients in response to a glucose load and to a protein load. No difference could be found and the endorphin levels were not elevated as expected from animal work. 2) Both groups of patients were given loading tests with cornstarch vs cooked corn, rice starch vs cooked rice, and potato starch vs cooked potato. These tests will be repeated in these same individuals as they lose weight toward normal. The glucose and insulin responses are followed. The results on these patients will also be compared with those obtained in glycogen storage disease patients who lack the whole control loop of blood glucose regulation.